Water heater



4 Sheets-Sheet l ZIJ, Fave/y.

A JOM?, 15u65 NDV. 16, 1943- J. w. FARREN ErAL WATER HEATER Filed oct.25. 193s w. w, ma 1W. FARREN'ETAL WATER HEATER Filed Oct. 25, 193 9 4Sheets-Sheet 2 NGV i6 w43 J. w. FARREN ET AL.

WATER HEATER Filed oct.

4 Sheets-Sheet 5 fa/@zionikfO/ZIZ Z( 7"?"6/2 Hgga/Ood 072,22@

TTORNEYS.

@65e/ll BY dem@ Patented Nov. 16, 1943 WATER HEATER John W. Farren,Russell W. Heywood, and James F. Donnelly, La Porte. Ind., assignora toBastian-Morley Co., Inc., La Porte, Ind., a corporation of IndianaApplication October 25, 1939, `Seriali No, 301,134

16 Claims.

Our invention relates to *water heaters and means for controlling flowof air thereto for combustion purposes, and it has to do particularlywith water heaters of the intermittent ring type that embody a storagetank, a main burner of the so-called on and off type located in acombustion chamber, and a flue which extends from the combustion chamberlengthwise of and in heat transfer relation to the storage tank.

Conventional devices of the foregoing character usually includetemperature controlling means adapted to shut off the gas to the mainburner when the temperature of the water in the tank is raised to apredetermined point and to cut in the burner when the temperature of thewater drops below that point, the burner being equipped with a small,constant-burning pilot burner for igniting the fuel (gas, for example)in the main burner when the latter is turned on by the temperaturecontrolling means. Also, the combustion chamber of such heaters islocated at the bottom below the storage tank, and it is fully open atthat .of heat from the water, particularly during off periods oftheburner. This loss is due mainlyto air passing directly and in anuncontrolled manner to the combustion chamber and thence into andthrough the flue, the amount of air naturally being in excess of thatrequiredl to support combustion in the pilot burner. formed Vof a heatconducting metallic material and, since the water in the tank is incontact with at least one wall of the flue and this water is hotter thanthe air passing through the flue during the off period of the burner,there is a direct transfer of heat from the water in the tank to theflue contents, which results in a considerable loss of heat from thewater. These conditions are induced in part by the small pilot burnerflame which burns at all times, in that it is sulcient to heat the airin the combustion chamber to a point Where its density, compared to thatof the air externally of the heater, is such as to induce an upward owof air through the flue. Also, the amount of heat loss from this causeis proportionate to the amount (including excess) passing through theflue during the ofP periods, and any material reduction in air flow willresult in an increased over-all heater efflciency.

In some heaters of the foregoing character, flue means are employedwhich serve to more efficiently effect a transfer of heat from the flueThe nue is gases to the water, such, for example, as disclosed in UnitedStates Letters Patent No. 1,947,606, dated February 20, 1934; but, forthe same reasons,such structures, when excess air, as above stated, ispassed through the ue, as during the od burner periods, serve totransfer a greater amount of heat from the water. to the upwardly movingall;` with resultant greater heat loss.

In some instances, it has been proposed to overcome such loss by the useof automatic dampers, and the like, adapted to open when the main burneris on, and to either shut off' air entering the combustion chamber orclose the exit of the flue when the burner is ,o Such devices, whileefficient in some respects, are objectionable because, in case offailure of the same to open at the proper time, incomplete combustionand explosions may occur.

One of the objects of our invention is to provide an improved heater oithe foregoing character which isy of simple and inexpensiveconstruction, is highly emcient in operation, and whichincludes new andnovel means for reducing heatV loss by limiting the flow of air to thecombustion chamber` and through the flue during the off periods f themain burner to substantially the minimum amount of ai: required foroperation of the pilot burner.

.Another object is to provide a heater having a ue with means foraccomplishing a highly effective transfer of heat units from the uecontents to water in the tank and which, at the same time, is providedwith air control means of such character that loss of heat from theWater by the tendency of the flue means to reverse the heat transferfrom the water to the ue contents during off" periods of the main burneris minimized, thereby increasing the thermal and service erliciency ofthe heater.

A further object is to provide a novel means for supplying secondary airfor combustion purposes, the arrangement being such that the amount ofair admitted to the combustion chamber and, in tum, passed through theue is controlled by the combustion requirements of the burner and isllimited to substantially that amount required for combustion, whereby agreater utilization of the lheat units discharged by the burner isexperienced and the water in the storage tank is heated more quickly andis maintained in a desired heated condition for longer periods lof timewith less fuel consumption. Y

Still another object is to provide siphonic means .of the foregoingcharacter so constructed and arranged that, as lthe burner requirementsour invention.

creased, the flow of air through the flue isincreased. To this end, we,preferably, provide an inverted Siphon-type or U-shaped passage throughwhich all air for combustion purposes must pass under the siphoniccontrol of flue gases discharged from the flue. This U-shaped pas sageincludes a so-called cold leg or air shaft open at oneend to theatmosphere and connected at its other end to the combustion chamber anda so-called hot leg or flue leading from the combustion chamber, the airshaft being of such size and capacity relative to the ue that it createsa drag condition for controlling the flow of air therethrough.

Additional objects are to provide trap means for supplying air to acombustion chamber and by which heat loss through such air is minimized;to provide a heater so constructedand arranged that all operating partsare completely enclosed, providing a compact structure of improvedappearance; to provide a heater of the foregoing character wherein thefuel control devices are located in the air shaft leading to thecombustion chamber, so that they are swept by incoming secondary air andare maintained in a comparatively cool condition; to provide an.improved form of heater casing that may be located in close proximity toa floor surface without danger of overheating: and to .provide an aircontrol for an intermittent iring type of water heater which includes apassage having connected hot and cold legs, the hot leg beingconstructed and arranged to minimize the excess air admitted during theon periods of the burner and the' cold leg being constructed andarranged to minimize the excess air admitted during the off" y line 3-3of Fig. 1;

Fig. 4 is a vertical sectional view, partially in 50 section, of anotherform of water heater embodying our invention; and

Fig.'5 is a vvertical sectional view of `still another form of waterheater structure embodying v Referring particularly to the structureshown in Figs. 1 to 3, inclusive, it includes a cylindrical tank I0surrounded, in spaced relation, by a cylindrical shell II, the spacebetween the tank and shell being filled with an insulating material I2.The side walls of the tank I0 and shell II are extended downwardly as atI 0* and IIl, respectively, beneath the bottom IIIb df the tank to form,in part, a comparatively shallow combustion chamber I3. The tank I0 andshell II are supported by a cylindrical, imperforate pan-like bottommember I4 upon which the lower edgess of the tank and shell side wallsseat. The bottom member I4 is supported upon legs I5 which 'space theheater as a whole from the supporting 70 floor surface. The combustionchamber' I3 is provided with a bottom in the form of a pan or plate-likemember I9 supported above and in spaced relation to the bottom member Iland rorming with the latter an air space, the plate 76 member I9 havingan opening II located near its central portion leading into thecombustion chamber I3. It'will'be seen that, with this arrangement, theonly inlet of air to the combustion chamber is through the opening I'Iand the space II therebeneath, which space is closed of! from theatmosphere except through an air shaft, which will be described later.The lstorage tank I0 is provided with the usual cold water inlet I9 andhot water service outlet' I9.

The-heater structure is further provided with a cylindrical iluestructure 20 extending vertically or lengthwise through the interior ofthe tank I0 so that it is surrounded by the water in the latter. Theflue 20 is so arranged that its lower end terminates in the bottom II)hof the tank, where it is connected directly to the combustion chamberIl, while its lupper end terminates in the top of the tank I9, where itis connected by an additional flue connection 2| passing through theouter shell II anda. draft diverter 22 to` a discharge stack (notshown). With this arrangement, heat from the hot gases of combustionpassing outwardly through the flue 20 are transferred to the water inthe tank surrounding the flue. In the particular arrangement illustrated(Fig. 1), the transfer of heat from the ilue products is amplified andimproved by employing an additional heat transfer shell 24 extendinginto the fiueway and bonded thereto for heat transfer purposes., aswell`as for the better distribution of the heated gases in the flue, allas more particularly and fully set forth in United states Letters PatentNo. 1,947,-

606, granted to Bastian-Morley Company on February 20, 1934. In thisarrangement, an efficient heat transfer is provided for Without undue4restriction to iiow of the gases through the nue, but sufficientrestriction is offered to mini-- mize excess air in the flue productswhen the burner is in its "on position and the heating of the water isin progress.

We have illustrated our invention, in Figs. 1 to 3, inclusive, as usedin connection with a heater having a burner 25 supported upon the platemember I9 forming the bottom of the combustion chamber I3. Although theburner shown .is adapted for gas as a fuel, it is to be understood thatany other desired fuel and burner construction may be employed with goodresults. The burner 25 is. preferably, but not necessarily, of the typedisclosed in United States Letters Patent No, 1,753,962, granted toBastian-Morley company on April 8, 1930, and it includes a manifold 29,a plurality of upstanding burner nozzles 21 and a pilot burner 28. Gasis furnished to the main burner manifold through suitable piping 29having therein a valve mechanism 30 controlled by a thermostatic element3i located within the water in the tank I0. The arrangement, which iswell known, is such that gas is cut into the burner through pipe 29 whenthetemperature of the water in the tank is reduced below acertain pointand gas is cut olf from the burner when the water in the tank'reaches a.predetermined temperature. Theavalve mechanism 30 is further controlledby the pilot burner 28 in such a way that so long as the pilot burner islighted so as to ignite gas admitted through the pipe 29 to the mainburner, the'valve mechanism 90 will permit the flow of gas when thethermostat 3| functions to open the main gas Valve, but if, for anyreason the pilot flame should be extinguished so that gas admitted tothe main burner would not be ignited, the pilot control functions toclose the main valve mechanism 30 and prevent the flow of gas to themain burner. The pilot control is of the thermoelectric type and it mayinclude (Figs. 1 and 3) a thermocouple element32 (Fig. 3) and amagneticvalve-operating unit 33 (Fig. 1) with proper electric connectionsincluding the pilot line 34 and other connections (not shown) enclosedtherein; the arrangement being such that, so long as the thermocoupleelement 32 is heated by the pilot flame, the magnetic unit 33 isenergized sufficiently to hold its valve (not shown) of the valvemechanism 30 open and permit the flow of gas, but in the event that thethermccouple element 32 should become cooled by extinguishing the pilotname, the magnetic unit would become deenergized, permitting its gasl:flow control valve to close. In that event, no gas, regardless of theposition of the valve controlled by the thermostatic element 3l couldnow to the burner. Since walls of the tank IIJ and shell II. The memberthis control mechanism may take any desiredL and well-known form, itwill readily be understood by those skilled in the art and we do notbelieve it necessary to go further into details-'in showing anddescribing the same.

In carrying out our invention, we control the :dow of secondary air tothe combustion chamber i3 in such a way that only substantially thatamount of air required for combustion is admitted, whereby, during the"o periods of the burner, a minimum amount of Asecondary air is admittedthereby limiting the amount of air passing through the ue to theminimum. It will be seen from the foregoing description that burner isarranged for intermittent ring thereby t providing so-called burner onand burner oil periods. The thermostatic control for the main burner is,preferably, of the so-called snap-actionthe contour of the outer shell.

type, so that the burner is turnedd and on practically instantaneously,the arrangement being such that the burner is either on full or is' oientirely. By thus limiting the amount of air admitted, as well as thatwhich must eventually exit through the nue 20, we reduce heat lossthrough the flue products to a material extent during the off periods ofthe burner. The foregoing air-limiting control feature is important inthe use of any arrangement wherein heat from the products of combustionare passed through or along a wall surfaceV separating the ue productsfrom the water in the tank; and it jis especially important in the useof a ue structure of the character above described, since the heattransfer ability of such nue structure is reversed when excess cold airis passed through the flue, with the result that heat is rapidlyextracted from the water in the tank surrounding the iiue. Thiscondition, if permitted to exist, would cause a materialemciency-lowering heat loss.

In controlling the air admitted to the heater as above mentioned, weemploy an inverted-` siphon or U-shaped passage means. One leg (theso-called cold leg) of this passage takes the iorm of a cold air inletpassage or shaft 35, and the other leg (the so-called hot leg) takes theform of the ue passage 20B, the two legs being joined together tocomplete the U-shape by the Acombustion chamber I3 and the space IItherebeneath. Substantially all of the air admitted to the combustionchamber I3, for combustion purposes or otherwise, must pass through thecold leg of this U-shaped passage. l

Specifically, the air shaft takes the frm of a tubular member 36,preferably of oblong, crosssectional shape, and it is disposedsubstantially parallel with the ilueway 20B 'between the side ashell-carried hood 38 which is wide enough to extend over the top of theupper end of the shaft, and laterally'thereof beyond the outer shell I Ito provide an air inlet 39 located laterally of the shaft 35 and at sucha position that the air iiows upwardly, then laterally and downwardlyinto the air shaft. f

Although the combustion chamber I3 is normally connected with theatmosphere only through the shaft 35, it may be desirable, at times, tohave access to the burner for repair and other purposes. To this end, weprovide adjacent the combustion chamber a doorway 40 leading through thesections I I8 and IIJa of the outer shell and tank(walls. The doorway,which is preferably of rectangular shape, is formed by a rectangularlyshaped casing member lil in which is received a rectangularly shapeddoor d2 curved to The door ft2 is of the friction-lit type and itincludes a metallic section 42a and an inner insulating section 32h and,with the door in place, its inner or insulating-section is adapted toseat firmly against a flange (i3 extending at substantially right anglesfrom and around the door casing il (Fig. 3) at a point intermediate theinner and outer edges of the doorway. The door is held in place Withinthe opening by a hinge-like unit it at one side and a rotatable latchunit 45 at its other side. The hinge unit member 44 includes one or morepins 46 engaging suitably provided openings in the adjacent part of thecasing member I. The latch 45 may include a rotatable latch element Allcarried by a rotatably mounted handle 48, the latch being adapted toenter a suitably provided slot in the adjacent part of the doorv casing4I. To place the door in position, the pins or prongs "36 are iirstinserted in their openings and the door then rocked inwardly and pressedinto tight seating engagement with the flange 43, after which the handleIIB is turned to move the latch 4l to its latching position. When thisis done, the doorway is sealed substantially airtight, but it mayreadily be removed by releasing the latch structure.

In the use of the structure above described, as-

suming that the main burner 25 isl on, the

heated gases` discharged from the burner pass upwardly into and throughthe ueway 20a. The nue products are heated suiciently to lower theirdensity tothe point where an updraft is created in the ueway 20B,causing suilicient air to be drawn down the cold leg shaft 35 to supportcombustion. In this operation, it is to be understood that the size ofthe inlet opening to the cold leg or shaft 35 is substantially 'inproportion to the volume of gas to be burned. The U-passage (35, I'I,I'I, I3, 20a) acts as an air siphon, the cold air drawn in plus the gasfed to the burner being substantially equal in amount to the-gasesdischarged through the llue; and, since the cold air inlet isproportionate to the volume of gas to be burned, the air thus admittedis substantially only that required for complete combustion of the gasthen being discharged by the burner. Due to the siphoni-c action set up,the admission of secondary air depends upon the displacement of gases inthe ue, and only when the flue gases are being displaced is coldsecondary air drawn in; and, if the gases discharged by the burner weregradually reduced, with a proportionate reduction in displacement ofgases in the ilueway, there would be a correspondingreduction in theamount of air drawn into the heater. Wherefore, when the main burner isturned oi'f by the temperature control means and only the pilot burnerremains burning, the secondary air requirements are reduced to the veryminimum and only that minimum requirement of air is supplied. When thepilot alone is operating, the ue products are still heated to some (buta lower) extent, thereby lowering the density of the flue productssufiiciently to create an updraft in the iiue 20H; however thetemperature of the gases entering the hot leg or flue 2lia issufficiently low to create only a slight updraft therein, therebycausing but little cold or secondary air to be admitted through the coldleg to the combustion chamber I3. A drag is imposed by the cold leg and,under the foregoing conditions of operation and in furtherance of thesiphonic action that takes place, this drag aids in the foregoing resultso that the amount of air entering the flue 20 or hot leg is reduced tonear the minimum with a minimized loss of heat on account of transfer ofheat from the water surrounding the i'iue 20 to the flue products.

By way of example, we have found that our purpose may well be served byemploying a water heater construction including a storage tank I ofapproximately 28 gallons capacity; a burner 25 having a rated capacityof approximately 27,000 B. t. u.s located inv a combustion chamberapproximately 14 inches in diameter and 8 inches in height; a flue 20 ofapproximately 42 inches and having a cross-sectional area of ap'-"proximately 7 square inches; and an air shaft 35 approximately 52 inchesin length with a cross-sectional area of approximately 5.75l squareinches and having an inlet approximately 5.75 square inches in area. Inthe use of such structure, the standby loss is reduced more than 2 percent, asa result of which an operating efficiency of at least 81A percent more than possible with prior heaters is obtained. It is to beunderstood that the foregoing structural dimensions are not to be in anysense limiting because they are given merely by way of illustration and,while the dimensions stated are capable of producing excellent results,they may be varied in some or all instances with good results andwithout departing from our invention.

Our invention is equally well adapted for use A with a heater embodyinga so-called ioater type of storage tank. Such a structural adaptation isillustrated in Fig. 4. The structure there shown includes a cylindricalstorage tank 50 surrounded, in spaced relation, at its top and sides bya cylindrical shell or liner 5l, which, in turn, is surrounded byanother cylindrical shell 52 in spaced relation, providing a spaceshells, forms a combustion chamber 55. the bottom of which is closed bya panor plate 58 having an opening 51. An imperforate bottom pan 58carried -by legs 59 supports the shells 5I and 52 and, in turn, the tank50, as in the firstdescribed form.

A burner 60 similar to the burner 25 (Fig. 1) is mounted in thecombustion chamber 55, and it may be controlled in a manner similar toth'e previously described burner structure. The spacing of the shell 50and liner 5| provides a flueway 5I connected at its lower end withythecombustion chamber 55 and at its upper end with an outlet flue section52 and a draft' di-. verter 63 leading to a stack (not shown).

Air is supplied to the combustion chamber 55 through an air shaft 64similar to the air shaft 35 (Fig. 1) and located in the insulation be-`I l tween the shells 5l and 52. The outer end of the shaft 64 isconnected to atmosphere through a hood 64 and its irmer end is connectedto the combustion chamber 55 through a space 55 `similar to the space i1(Fig. 1). The air shaft 64, space 65, combustion chamber 55 and fluewaySi constitute Aa continuous U-shaped siphonic passage. One of the maindifferences between this structure and/ that of Fig. 1 is that the hotleg or flue of the U-shaped. siphon passage takes thepform of a fluewaypassing around the tank wall instead of through it. overheating of theshaft 64 is avoided by locating it in the insulation in such a way thatan insulated space 56 is provided between it and the fiueway 5i.Obviously, any other suitable means may 4be employed for, preventing orminimizing any tendency to preheat the air flowing through the shaft 54before it reaches the combustion chamber.

The heater structure shown in Fig. 5 is similar to the structure firstdescribed except that it provides an air flow arrangement wherein thegas control devices are located directly in the path of incoming coldair so that they are maintained in asubstantially cold condition while,at the same time, providing a heater wherein practically all of the,operating parts are completely enclc ed. thereby not 'only enhancing themechanical utility of the structure but also its appearance.

The structure shown in Fig. 5 is similar to that of Fig. l except that arectangular shaped outer shell 10 surrounds a cylindrical storage tank1i. Also, in this form, the cold leg of the U-shaped slphon passagetakes the form. preferably, of a rectangularly shaped air duct section12 near the upper front portion of the outer shell 10, the shell walladjacent the' same being provided with a plurality of air louvres 13.Beneath the air duct 12, and extending substantially to the bottom ofthe heater, is anotherand wider and deeper air duct section 14 connectedat its upper end to the lower end of the air duct section 12. The lowerend of the air duct section 14 is covered by a plate 15 which alsoextends throughout the width and depth of the heater shell 10, in whichplate are located a plurality of openings 18 connecting the shaftsection 14 with a space 11 therebeneath.

- The space 11 is connected with the combustion chamber 18 by an opening18 in the plate 15, whereby the cold leg (sections 12 and 14) of theU-shaped siphon passage are connected to the hot leg (fueway by' way ofthe openings 18, the space 11 and the opening 18 in the combustionchamber 19.

A burner 8| similar to the burner 25 (Fig. 1) is located in thecombustion chamber 19 and the 82 and its connections are located in theair inlet section 'Il directly in the path of the cool air" owingtherethrough so that it and its connections are constantly sweptrby coolair and are thus kept in the desired cool condition notwithstanding thefact that they are located within the heater shell. where they cannot beseen. Access to the valve mechanism is had through a rectangular shapeddoor 84 which is, preferably',

of the friction fitting type similar to the door t2` shown in Figs. 1and 3. Access to the combustion chamber 19 through the cold air section14 may 1 be had through an additional friction t door 85 mounted in theback wall of the section 14 and the side wall of the tank 1| formingaside wall of the combustion chamber 19. i

The heater structure shown in Fig. 5 may be mounted in such a way that`the combustion chamber 19 is in close proximity to the supporting .doorsurface, and it may be desirable to provide additional insulating meansto prevent any possible overheating of the floor surface. To that end,we may employ a heat baille plate 8B detachably supported below andshaped similarly to the opening 18. The baille plate B6 is suppoi'tedbyhanger legs 86a thereon that pass through the opening 18 and engage theupper surface of the plate 15. A deilector plate 81 is supported beneaththe baiiie 86 by a plurality of brackets @d carried by the plate 15,as'shown, or by the side wall of the shell, or in any other desiredmanner. The baille plate 8E and plate 81 are, preferably, formed ofmetal of any desired kind adapted to serve as a radiant heat deflector,and the advantages thereof will be well understood. We'may additionallymount upon the plate 81, directly beneath the combustion chamber,another plate 89 which is shaped to provide, when assembled with theplate 81, a dead air space 90. 'Ihe use of the plates 86, 81 and 89entirelyavoids thepossibility of overheating the floor surface, allwithout undue restrictionin the flow oi' air from the cold leg of theU-shaped siphon passage to the combustion chamber portion thereof. Otherthan abovedescribed, the construction and operation of this fornrofdevice-is the same as that shown and described in connection with Fig.1.

We believe that the operation and' advantages of our invention will bereadily understood from the foregoing description. The air that must beheated by the burner, as'well as the air passing throimh the flue, islimited to substantially only that required. for combustion at allstagesof burner operation. This results in a maximum transfer of heatfrom'the flue products to the water and prevents, or at least reduces tothe minimum, any tendency for' backfiow 'of heat from the water to theflue products during the "off" period of the burner. 'Ihe added eiciencyinsured by our invention makes possible a more economical operation, allwith the minimum oi attention on the part of the user.

It is to be understood that, while we have shown and described three.forms of structure embodying our invention and have giYen one typicaldimensional embodiment, other changes in details, arrangements anddimensions of parts may be made without departing from the spirit andscope of our invention as defined by the claims that follow.

v We A l. Water heater structure comprising a storage tank. meansproviding a combustion chamber bel Aneath said tank, means providing aiiueway extending upwardly from said combustion chamber v A lengthwiseof said tank, a burner in said combustion chamber, means for supplyingfuel to said burner, and means for gravitationally Supplying air to saidcombustion chamber for combustion purposes which includes an air shaftextending substantially parallel with said iiueway and externally ofsaid tank and having its upper end connected to atmosphere. and theother end connected to said combustion chamber, a shell surrounding saidtankandconibustion chamber-,said shaft being positioned within saidshell and spaced from said tank and ueway, said shaft being the only airinlet to said combustion chamber and being so constructed and arrangedthat the ilowof air therethrough is self-induced solely bythe normaldisplacement of the products of Icombustion in said combustion chamberand llue- Way.

2. Water heater structure comprising a storage tank, means providing acombustion chamber beneath said tank, 'meansprovding a flueway ex-ltendingupwardly from said combustion chamber lengthwise of said tank, aburner in said combustion chamber, means supplying fuel to saidburner,and means for gravitationally supplying air to said combustion chamberfor combustion purposes which includes an air shaft extendingAsubstantially parallel with said uewayand externally of said tank andbeing substantially the only'air inlet to said combustion chamber, saidshaft having an-inlet at a height adjacent the exit of said iiue, andhaving an outlet connected directly to said combustion chamben-a shellsurroundingsaid tank and combustion chamber, said shaft being positionedwithin said shell and spaced from s'aid tank and said ueway, said shaft,combustion chamber and flue constituting '.-a U-shaped or invertedsiphonic passage so con- "structed and arranged that the iiow of airtherev"through is self-induced solely by the normal displacement of theproducts of combustion in said combustion chamber and iiueway.

3. A water heater which comprises a storage tank, means providing acombustion chamber directly beneath said tank, means providing aflueyway extending vvertically from said combustionv -chamberl en-dwiseof and beyond said tank, a shell surrounding lsaid tank and combustionchamber and so constructed and arranged that it seals said tank andchamber from the atmosphere, a burner located in said combustionchamber, and means for gravitationally supplying air to said combustionchamber and burner which comprises a vertically disposedair-shaft-forming member mounted between said shell and tank and spacedfrom said tank and said fiueway, means supported by said vshellformingan air inlet to said shaft, and conduit meansextending'horizontally and forming an exit from said shaft leading intosaid combustion chamber.

4. lA water heater which comprises a storage tank, means providing acombustion chamber directly beneath said tank, means providing a iiuewayleading vertically fromsaid chamber endwise .of and beyond saidtank, aburner .located in said chamber, an `outer shell completely enclosingsaid tank and combustion chamber, and

ently of and within the connes of said shell a subv stantially verticalpassage leading from a point adjacenta the exit of said fiueway to thelower part of said shell, means providing an inlet of xed size to theupper end of said passage, and means providing an exit from the lowerend of said passage leading to said combustion chamber, said passage,yexit means, chamber and flue providing a continuous, U-shaped passageconstituting substantially the only source of air entry and flow throughsaid heater.

5. Water heater structure comprising a water storage tank, meansproviding a combustion chamber directly beneath said tank, meansproviding a fiueway leading upwardly from said chamber through the waterin said tank, a burner and combustion chamber, means for admitting airto said chamber which includes means inside said shell forming a passageextending substantially parallel with said fiueway and externally ofsaid tank and spaced from said tank, and means connecting the upper endof said passage with the` said chamber, ashell surrounding said tank andcombustion chamber and means for gravitationally controlling theadmission oi air to said chamber for combustion purposes and controllingthe exhaust of burned gases which comprises a U shaped, invertedsiphonic passage including a hot leg in the form of a fiueway extendingsubstan- .tially vertically from said chamber lengthwise of said tank,and a cold leg in the form oi a passage positioned inside of said shelland spaced from said tank and fiueway, said passage extendingsubstantially parallel with said hot leg and having its inlet endterminating at a height near the height' of the upper or exit end ofsaid hot leg, and said cold leg having its outlet end connected to saidchamber at a point below the inlet to 3said flue whereby saidchamber'completes said siphonic passage by connecting said legs, thesaid U-shaped passage constituting substantially the sole source of airentry and flow through said heater.

'7. Water heater structure comprising a storage tank, meansproviding aclosed combustion chamber beneath said tank, a shell surrounding saidtank and combustion chamber, a flue member extending upwardly from saidcombustion chamber in said chamber, a shell surrounding said tanklongitudinally through said tank in heat transfer contact with the watertherein and having an upper exit, a burner in said combustion chamber,means for supplying fuel to said burner, and means by whichsubstantially all of the air for combustion purposes is supplied to saidcombustion chamber. which means includes an air shaft member extendinglongitudinally and exteriorly of said tank and providing an air shaftextending substantially the length oi said heater struct-ure parallelwith said flue member and having its outer end connected to atmospherenear the height of the exit of said iiue member and its inner endconnected to said combustion chamber at a point below the connectionbetween the combustion chamber and said flue member, said air shaft'member being disposed between said tank and said shellin spacedrelation to said tank. y

8. Water heater structure comprising a storage tank, an outer shellmember surrounding said tank in spaced relation thereto, insulationmeans disposed in the space between said tank and shell, means providinga closed combustion chamber beneath said tank and disposed inwardly ofsaid insulating means, means providing a ilueway leading ,verticallyfrom said chamber endwise of and beyond said tank, a burner in saidcombustion chamber, means for supplying Afuel to said burner, and meansfor supplying substantially all of the air to said combustion chamberfor combustion purposes, which includes a tubular member surrounded bysaid insulating means disposed between said tank and shell and providingan air shaft extending substantially throughout the length of the heaterstructure in substantially parallel relation to said fiueway, the upperend of said shaft being connected directly to atmosphere with its lowerend connected to the lower portion of said combustion chamber.

9. Water heater structure comprising a water storage tank, meansproviding a combustion chamber directly beneath said tank, meansproviding a ilueway I leading upwardly from said chamber through thewater in said tank, a burner in said chamber, a shell surrounding saidtank and combustion chamber, and means for admitting air to said chamberwhich includes members forming a passage extending substantiallylparallel with said ueway and externally of said tank, said members beingpositioned inside said shell and spaced from said tank, means connectingthe upper end of said passage with the atmosphere at a point adjacentthe upper end of said ilueway and its lower end with said chamber at apoint beneath the latter, said passage, chamber and ilueway beingconstructed and arranged to provide a continuous inverted siphonicpassage of which said air passage constitutes a cold leg andsubstantially the only inlet for air to said combustion chamber, saidfiueway a hot leg, and said chamber a connection between said legs, saidpassage inlet having an area proportionate to the area of said fiuewayand the volume of'the gases to be burned by said burner to insure asiphonic action in the siphonic passage.

10. Water heater structure comprising a water storage tank, meansproviding a combustion chamber beneath said tank, a burner located insaid chamber, means for controlling the admission of air to said chamberfor combustion purposes and controlling the exhaust of burned gaseswhich comprises a U-shaped, inverted siphonic passage including a hotleg in the form of a fiueway extending from said chamber through saidtank, and a cold leg in the form of a passage extending substantiallyparallel with said hot leg and disposed exteriorly of said tank andspaced from the wall thereof, said cold leg having an inlet at its upperend connected to atmosphere near the height of the exit of said fiuewayand its outlet end connected to said chamber at a point below theconnection between the combustion chamber 'and said fiueway whereby saidchamber completes said siphonic passage by connecting said legs, a shellsurrounding said tank and combustion chamber, said. passage having atleast a tank and providing with the side wall of the latter a ilueway,means providing a closed combustion chamber beneath said tank and' withwhich the inner end of said flue communicates, a second shellsurrounding said combustion chamber and said first shell means forsupplying fuel to said burner, iiue discharge means connected with theouter. end of said flueway, and means for supplying to said combustionchamber substantially all of the air used for combustion purposes, whichcomprises an elongated member located exteriorly of said first shellmember and spaced therefrom and extending substantially throughout thelength of the heater structure with the outer end of said shaftconnected directly to atmosphere and its inner end connected to saidcombustion chamber below said flueway,

said elongated member being positioned inside of said second shell.

12. Water heater structure comprising a storage tank, a shell membersurrounding said tank and providing with the side wall of the latter aueway, means providing a closed combustion chamber beneath said tank andwith which the inner end of said flueway communicates, means forsupplying fuel to said burner, ilue discharge means connected with theouter end of said ueway, means for supplying to said combustion chambersubstantially all of the air used for combustion purposes, whichcomprises an elongated member located exteriorly of said shell memberand extending substantially throughout the lengthof the heater structurewith the outer 'end of said shaft connected directly to atmosphere andits inner end connected to said combustion chamber below said flueway,and another shell member surrounding said iirst shell member in spacedrelation thereto and enclosing said air shaft member, and insulatingmeans disposed in flueway around the entire side wall of said tank,

said tank having a bottom wallwhich together with the lower portions ofsaid shell members and said bottom closing means forms a combustionchamber, flue discharge means connected with the upper end of said fluespace, a burner located in said combustion chamber, means for supplyingfuel to said burner, and means for supplying subn stantially all of theair to said combustion chamber for combustion purposes, which comprisesa member disposed between said shell members and insulated therefrom bysaid insulating means and extending substantially throughout the length.of said shell members, means connecting theoutlet end of said shaftdirectly with the atmosphere. andy means for connecting the inner end ofsaid shaft member with said combustion chamber at a point below saidiiue space.

14. Water heater structure comprising a storage tank, a first shellmember surrounding said tank in spaced relation thereto and formingtherewith aflueway, said shell member extending below said tank andforming with the latter a combustion chamber, imperforate means forclosing the bottom of the combustion chamber, a vertical air shaftconstituting substantially the only inlet for air to said combustionchamber and having its upper end connected to the atmosphere and itslower end to the bottom of said combustion chamber so thatsaid shaft,combustion chamber and fiueway constitute an inverted siphonic passage,a second shell member surrounding said first shellmember and spacedtherefrom to form an insulation chamber, said air shaft being disposedbetween said rst shell member and said second shell member andpositioned in said insulation chamber.

15. Water heater structure comprising a storage tank, means providing acombustion chamber directly beneath said tank, a flue leading from saidchamber through said tank, a burner in said chamber, an outer shellenclosing said tank and chamber and extending below the latter andadapted to support the heater upon a surface, a bottom member carried bysaid shell above its lower edge and providing a bottom for said chamber,said member having an opening leading into 'said chamber, and means forsupplying substantially all of the combustion air to said chamberthrough said opening which includes a member located between said shelland tank and spaced from said tank and providing an air shaft extendingfrom near the top of said tank to said bottom member, said bottom memberhaving one or more openings therein connecting the lower end of saidshaft with said opening leading into said chamber.

16.` Water heater structure comprising a water storage tank, meansproviding a combustion chamber beneath said tank, a shell having aclosed bottom enclosing said tank and chamber and shutting off the samefrom the atmosphere, a ilue member extending upwardly from said chamberthrough the water in said tank, a burner in said chamber, and means forsupplying substantially all of the air to said chamber for combustionpurposes which includes means spaced from said tank and forming apassage between said shell and tank leading from near the top of thelatter to near its bottom, the upper part of said passage beingconnected to the atmosphere and its lower part being connected to saidchamber, and means including fuel conduits connected to said burner andadapted to cut in and out said burner according to the temperature ofthe water in said tank, said latter means being disposed in the lowerpart of said passage where the same is swept by air incoming forcombustion purposes.

JOI-DI W. FARREN.

RUSSELL W. HEYWOOD.

JAMES F. DONNELLY.

